Electromagnetic (EM) telemetry in drilling operation environments uses a drill pipe and a formation in which a well bore is drilled as two conductive paths for propagating an electromagnetic field. Owing in part to high conductivity of the formation and the drill pipe, leakage currents and the skin effect result in a usable bandwidth that is in the range of less than 50 Hz; typically 5-25 Hz.
Some disadvantages of such EM telemetry includes shunt losses back to the drill pipe from the formation, series resistance through earth formations, and field dispersion that results from lateral spreading out of conduction in the formation. These factors negatively affect signal strength and limit the distance of effective signal propagation.